1. Field of the Invention
The present invention relates to a communication technique for performing a bidirectional communication via a network having a 1-to-n configuration, such as a CATV network, etc., and more particularly to a communication technique with which a communication channel is shared by sound and data.
2. Description of the Related Art
In recent years, a communication system for simultaneously implementing a bidirectional service such as a telephone service, a data communication service, etc. by using a CATV network having an existing 1-to-n broadcasting type configuration has been developed.
In such a communication system, particularly in a data communication service, it is expected that a communication channel is used as efficiently as possible and a faster communication is implemented.
Furthermore, there is the demand for the capability for providing data communication services of various communication qualities according to the requirements of service subscribers or service providers, such as the capability for setting each data communication service class by ensuring each communication speed, etc.
With a conventional bidirectional communication system, communication channels are allocated fixedly to respective sound and data in advance and the respective communications are made, when the sound and data are simultaneously transmitted.
This conventional system, however, has the problem that the communication channel allocated to the sound is not fully utilized and the communication channel cannot be effectively used if there is almost no traffic for the sound transmission due to the traffic""s concentration of the data transmission.
In a communication system using a network whose number of terminals to be connected is large such as a CATV network, etc., a communication channel must be effectively used in order to use a transmission bandwidth as efficient as possible because the above described concentration of the traffic can occur with a great possibility.
The above described conventional system has another problem in that it is impossible to provide a flexible communication service whose communication quality is set depending on a requirement of a service subscriber or a service provider, for example, a communication service whose communication speed is set depending on a requirement of a service subscriber, or a communication service whose communication speed is set to be different depending on a type of data to be transmitted.
The present invention was developed due to the above described background, and aims at allowing a communication channel to be shared by sound and data in order to efficiently use a transmission bandwidth, and allowing the communication channel to be dynamically allocated for sound transmission and data transmission in a communications system using a network whose number of terminals to be connected is large such as a CATV network, etc.
Furthermore, the present invention aims at allowing a communication channel to be allocated fixedly to a particular terminal in order to set a communication speed depending on a requirement of a subscriber, a priority process for setting a communication speed depending on a data type to be performed, and a transmission of unnecessary data to be restricted for improving transmission efficiency, etc., in such a communication system.
The present invention assumes a communication system which provides a bidirectional communication service simultaneously with a broadcasting type communication service from a center device to a plurality of terminals by using a 1-to-multiple broadcasting network configured between the center device and the plurality of terminals.
According to the present invention, the following control process is basically performed.
First of all, an idle/busy state of a first medium signal is detected in a center device.
Next, the detected idle/busy state is managed as first medium idle/busy information in the center device.
The first medium idle/busy information is then notified from the center device to the terminal.
Next, the first media idle/busy information that the center device and the terminal respectively store are updated in the center device and the terminal in synchronization with each other.
Then, in the center device and the terminal, an idle communication channel among the communication channels to be allocated to a first medium signal is allocated to a second medium signal based on the first medium idle/busy information that the center device and the terminal respectively store.
The transmission frame including a group of communication channels to which the first and second medium signals are allocated is communicated between the center device and the terminal.
As described above, according to the present invention, the center device and the terminal communicate the first medium idle/busy information in synchronization, so that the allocation of the communication channels to the first and second medium signals can be dynamically changed in a transmission frame based on the contents of the first medium idle/busy information. Consequently, a transmission bandwidth can be effectively used up to its maximum.